1. Field of the Invention
The present invention relates to a digital video tape recorder (hereinafter referred to as a VTR) and, more specifically, to a digital VTR capable of forming a reproduced image at high speed based on digital video information reproduced by a rotary head while a tape is running at high speed in the fast forward direction or in the rewind direction.
2. Description of the Background Art
In a conventional digital VTR for digitally recording video information, error correcting information is added to digital video information at every prescribed period, for example, at every block period provided by dividing 1 field period into some blocks. The digital video information with error correcting information added in this manner is rearranged by block unit of information, that is, interleave processing is carried out in order to prevent continuous inaccuracy in the reproduced images caused by dropout or the like. Thereafter, the error corrected and interleaved digital video information is recorded on a magnetic tape by means of a rotary head. A digital VTR in accordance with the standard of CCIR is disclosed as an example of such a conventional digital VTR in pp. 14 to 21 of "NHK Giken Geppo (monthly report of NHK laboratory)" published in Apr., 1986. In this digital VTR, information is recorded on a magnetic tape while a composite rotary head capable of simultaneously recording signals of 2 channels is rotated at a speed six times as fast as the field frequency. Consequently, 12 recording tracks are formed on a tape in 1 field period, with the central portion of each of recording tracks allotted as an area for recording digital audio information. Such a recording format is employed in order to ensure reproduction of audio signals by providing a relatively small audio information area at the center of the track with which the head is brought into contact more stably than the outer portions of the track. The necessary area for recording audio information is relatively small, as the amount of audio information is small.
However, when information recorded on the magnetic tape in such a format is reproduced at high speed, that is, when information is to be reproduced with the tape running at high speed in the fast forward direction or the rewind direction, it is difficult to form a reproduced image based on the information reproduced from the tape. More specifically, high speed image reproduction is possible to some extent when what is recorded is conventional analog video signals. However, in the digital VTR, it is difficult to form a reproduced image at high speed, since the digital video signals are interleave processed to be recorded as described above, and it is difficult to perfectly reproduce recorded signals if there happens to be an error, as the amount of information itself is small.